1. Field of the Invention
With reference to the field of art as established by and in the U.S. Patent Office this invention is believed to be found in the General Class entitled, "TOOLS" (Class 81) and more particularly in the subclass entitled, "crossed handles" (Subclass 415) and the subclass thereunder entitled, "joint detail" (subclass 416).
2. Description of the Prior Art
A careful pre-Ex search of the prior art was made and although box joint tools are well known, the use of a securing plate to hold the joint together that did not further require that the joint have a retaining shoulder or surface support for the two moving portions as is provided in a conventional box joint was not found. The construction of a conventional box joint requires that the box opening in one member be opened and distorted usually by heat and the other member be passed through said box opening. The joint is then brought to its finished condition usually by applying heat and pressure. This second heating affects the temper or hardness in the jaw ends.
The resulting box joint, although stronger than a lap joint, requires a difficult finishing of the contiguous members in the joint but the play in the joint is compensated for by a rivet or screw. The resulting joint tends to develop play at its inception or shortly after being put into use. Although careful and expensive fitting of the joint is made the resulting tool, after use, does not have the initial or the permanent accuracy desired in precision tools. In the tool to be hereinafter shown and described a precise ground joint with all surfaces precisely formed and sized is provided. A small degree of tightening adjustment is also available.
Box joints as used with pliers and tongs are shown in U.S. Pat. No. 259,886 to MATTHEY as issued June 20, 1882 and U.S. Pat. No. 2,948,962 to MANNING as issued Aug. 16, 1960. Also of note is U.S. Pat. No. 788,575 to BERNARD as issued May 2, 1905 and U.S. Pat. No. 914,417 to CRUZE as issued Apr. 6, 1909. Combination joints with a modified box with the cover plate riveted or screwed in place are shown. These joints, with additional plate securing means, do not contemplate the making of a box joint assembly with the members retained in position by formed and integral portions and with the securing plate preventing unwanted disassembly.